<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>css-notes</title>
  <style type="text/css">
    [title] {
      color: red;
    }
  </style>
</head>
<body>
<h1>可以应用样式：</h1>
<h2 title="Hello world">Hello world</h2>
<a title="百度" href="http://www.baidu.com">百度</a>

<hr />

<h1>无法应用样式：</h1>
<h2>Hello world</h2>
<a href="http://www.baidu.com">百度</a>
</body>
</html>
